I'm working on a Carlyle 5H60-2103 open drive compressor that has int. oil failure trips. It has HP80 and is used as a blast freezer to maintain -15F. Today we removed the back end plate containing the oil and suction sensor tubes and unloader adjustment spring. We checked it for possible cracks in the tubes, found none. We also pressurized the unloaders to see if they were leaking, they were not. The crankcase had very little oil left in it, we just added a gallon to it two weeks ago. There were filings in the oil, indicating internal wear. WE cleaned the sight glass, replaced the end plate and added oil to half of the sight glass (about 2 gallons of 150 oil). We started it back up and set the unloaders up based on suction pressure (about 8psi fully unloaded) and compressor current. Obviously we are pumping more oil out into the system than we are returning. I've thought about removing and cleaning the oil separator. My question is...the compressor is quite old and worn, is it possible for it to be running too hot, and thinning the oil so much that too much of it is being lost to the system? Should we be considering a new compressor? Is there anything else we can check? I'm going back tomorrow to monitor...any help would be greatly appreciated.